What you describe as intermitten makes me sure its your fuel pump. reason, loud pump, shitty acceleration. The pump is ok sometimes because it's condition worsens as it heats up. Running low amounts of fuel in the tank will increase your symptoms even more.
The fuel lubricates and cools the pump, so when you put in your new one, try to keep it above a quarter tank. The pump armature and bushings are likely worn from age and heat.
When you change the pump be sure to install a new fuel filter... very cheap.